In this paper we present our traffic generation platform, named D-ITG (Distributed Internet Traffic Generator). Its features are first described. We believe that some capabilities are in fact innovative, since no other traffic generator offers them. Then, we describe the original architecture of D-ITG, which allows our traffic generator to achieve high performance. We hint at a comparison with other traffic generators and conclude with the ongoing work to add new features.

Quality of Service Routing is at present an active and remarkable research area, since most emerging network services require specialized Quality of Service (QoS) functionalities that cannot be provided by the current QoS-unaware routing protocols. The provisioning of QoS based network services is in general terms an extremely complex problem, and a significant part of this complexity lies in the routing layer. Indeed, the problem of QoS Routing with multiple additive constraints is known to be NP-hard. Thus, a successful and wide deployment of the most novel network services demands that we thoroughly understand the essence of QoS Routing dynamics, and also that the proposed solutions to this complex problem should be indeed feasible and affordable. This article surveys the most important open issues in terms of QoS Routing, and also briefly presents some of the most compelling proposals and ongoing research efforts done both inside and outside the E-Next Community to address some of those issues. q

Abstract-The focus of this paper is on wireless mesh networks. In particular, we study the multi-radio case, given the considerable improvement in network throughput that multiple radios allow to achieve and the availability of cost-effective wireless devices. Interesting research problems are still unsolved in this field. Due to the scarcity of non-overlapped frequency channels and available radios per node, interference is still present, which cuts the achievable throughput down. As interference depends on how channels are bound to radio interfaces, a proper channel assignment scheme is needed to reduce the interference.In this paper we identify some key requirements of a channel assignment scheme. Accordingly, a centralized channel assignment algorithm is developed for multi-radio wireless mesh networks in order to maximize the throughput and address the interference problems. Finally, a performance study is presented to assess the effectiveness of our proposed algorithm.

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In the Cloud Computing paradigm there is an emerging Green Computing awareness, aimed at increasing the cost-efficiency of the underlying infrastructure. The pursued objective is to find the right compromise between the energy consumption and the perceived quality of service of the applications running in the cloud. Big data centers, along with the adoption of the virtualization technology, are increasingly experiencing the need to reduce consumption, because of both the environmental pollution and the economic concern. Among the novel techniques used to minimize the energy consumption wastefulness there is the Virtual Machines Consolidation, which leverages the VM live migration. The goal is to increase the overall cost-efficiency by reducing the number of active nodes. The main contributions of this paper are the proposal of a novel model for the consolidation problem and a Simulated Annealing based algorithm which solves it by evaluating the attractiveness of the possible VM migrations.

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Abstract-The availability of cost-effective wireless network interface cards makes it practical to design network devices with multiple radios which can be exploited to simultaneously transmit/receive over different frequency channels. It has been shown that using multiple radios per node increases the throughput of multi-hop wireless mesh networks. However, multi-radios create several research challenges. A fundamental problem is the joint channel assignment and routing problem, i.e., how the channels can be assigned to radios and how a set of flow rates can be determined for every network link in order to achieve an anticipated objective. This joint problem is NP-complete. Thus, an approximate solution is developed by solving the channel assignment and the routing problems separately. The channel assignment problem turns out to be the problem to assign channels such that a given set of flow rates are schedulable and itself is shown to be also NP-complete. This paper shows that not only the channels but also the transmission rates of the links have to be properly selected to make a given set of flow rates schedulable. Thus, a greedy heuristic for the channel and rate assignment problem is developed. Algorithms to schedule the resulting set of flow rates have been proposed in the literature, which require synchronization among nodes and hence modified coordination functions. Unlike previous work, in this paper a forwarding paradigm is developed to achieve the resulting set of flow rates while using a standard MAC. Index Terms-Multi-radio wireless mesh networks, channel assignment, physical model of interference, layer-2.5 forwarding paradigm.

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